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Re: Hyperbolic function identity

• To: mathgroup at smc.vnet.net
• Subject: [mg50962] Re: Hyperbolic function identity
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Wed, 29 Sep 2004 07:09:26 -0400 (EDT)
• Organization: The University of Western Australia
• References: <cjasqk$ns0$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

In article <cjasqk$ns0$1 at smc.vnet.net>,
 carlos at colorado.edu (Carlos Felippa) wrote:

> Why 
> 
>    FullSimplify[ArcCosh[1+z^2/2]-2*ArcSinh[z/2],z>0];
> 
> does not evaluate to 0?

Good question. Note that

  FullSimplify[TrigToExp[ArcCosh[z^2/2 + 1] - 2 ArcSinh[z/2]], z > 0]

does evaluate to 0.

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 6488 2734
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